Alarm device for prime movers



`March Z6,A 1957 `w. E. oAKEs 2,786,437

ALARM DEVICE: FOR'PRIME MovERs Filed April 15, 1955 INVENTUR. wil-[iam @n/@.5

ALARM DEVICE FOR PRIME MOVERS William E. Oakes, Edmonton, Alberta, Canada Application April 15, 1955, Serial No. 501,609

Claims. (Cl..116-70) This invention relates to an alarm and shut oit apparatus for a prime mover such `as internal combustion engines and the like.

Various means have heretofore been proposed for giving warning to an operator of a prime mover should its oil pressure fail or should its coolant temperature rise beyond a safe limit. However, despite the obvious advantages of devices of` this nature, they are not in general use largely because, it is believed, they are of costly and complicated structure and installation and are not of a fully dependable character.

It is an object of this invention to provide a simple, compact apparatus for installation in a prime mover and arranged to provide a Warning signal should the oil pressure of such prime mover fail ory should its coolant temperature rise beyond a safe limit, and further including simple means for manually shutting oi said signal and for automatically reactivating the apparatus.

Other objects, details and advantages of the invention will become apparent as this description proceeds with particular reference to the accompanying drawing in which,

Figure l is a sectional elevation of the apparatus in accordance with the invention,

Figure 2 is a sectional elevation of the apparatus shown in Figure l with parte thereof in another position,

Figure 3 is an elevation ofthe apparatus in association with a thermostat bleeder valve, illustrated in section, and

Figure 4 is a cross-sectional view of the apparatus shown in Figure l.

Referring to the drawing, pis a composite housing of generally cylindrical form and having a top member 2, a bottom member 3, and intermediate members 4, 5 and 6, such members being maintained in assembled order by means of the longitudinally extending bolts or rods 7. interposed between members 2 and 4 is a diaphragml 8. A second diaphragm 9 is interposed between members and 6 anda third diaphragm 10 is interposedbetween members 6 and 3. The diphragms may` beformed of any suitable ilexible material suchl as` rubber fabric or the like.

Mounted upon top member 2 is awhistle or likeraudible air-operable signal device il. A fluid passage i2 in member 2 communicates with Whistle` 11 to provide the actuating meanstherefor andwith thelower fiat surface of memberZ against whichA diaphragm 8 normally bears to close the opening of suchpassage 12, as shown in Figure l. Meanslfor resiliently urging diaphragrn into such normal position comprises a. piston 13 reciprocally mounted in a cylinder 14 formed inmember 4 and a spring 15 urging the piston` upwardly against diaphragm 8. Member 4 is recessed` about the upperv end of piston i3 to provide an annular chamber 16 below diaphragm 8.

Member 4 is also provided` witha chamber 17, the lower end of which is closed by memberS, A fluid passage 18 extends through members` 2 4 and 5, and has an opening 19 at vone end communicating with the lower surface of member adjacent the opening of passage 12;

'ice

Opening 19 is also closed by diaphragm 8 in its normal position, as described. Passage 18 has an enlarged opening 20 at its other end in the upper surface of member 5. Valve control means for opening 20 is provided and includes a valve seat 21 surrounding the opening, and a valve 22. The latter comprises a spindle 23 reciprocally mounted in member 5, a head 24 carried by one end of the spindle and engageable with seat 21 to close opening 20, and a disc 25 carried by the lower end of the spindle for engagement by diaphragm 9. The lower surface of member 5 is recessed at 26 to receive the disc 25. A spring 27 urges the valve into open position. An 0ring 28 on spindle 23 provides the necessary sealing means for the valve.

Member- 6 is provided with a chamber 29, diaphragms 9 and 1t) constituting the upper and lower walls thereof. Chamber 29 is arranged for constant communication with the lubricating oil system of an engine by means ofl a port 30 and conduit 31.

Member 3 is provided with an axial passage 32 in which is mounted a pilot valve 33 having a spindle 34 and head 35. A recess 36 in the upper face of member 3 provides a seat for head 35 which engages the lower surface of diaphragm 16. Spindle 34 has an annular recess 37, sealing means such as O-rings 38 and 39 being provided on the spindle above and below the recess as shown. A spring 40 urges the valve 33 in an upward direction. The lower portion of passage 32 below valve 33 has an adjustable bleeder port 41 leading to atmosphere through a port 42 in cover cap 43.

The portion of passage 32 bounded by the wals of recess 37 is in constant communication with a conduit 44 by means of a port 45. Passage 32 has a second port 46 arranged for selective communication by means of valve 33 with the portion of the passage bounded by the walls of recess 37, Port 46 communicates with chamber 16 in member 4 by meansA of a passage 47 extending through members 3, 6, S and 4.

A thermostatic valve unit 48 is incorporated in the system and comprises a casing 49 having a thermostatic element 59 depending from the lower portion thereof and arranged for position in the prime mover coolant system. The element 50 may be of the conventional gas-filled bulb type connected to a bellows 51. When the operating temperature of the coolant becomes excessive, the vapor pressure of the enclosed duid causes the bellows to elongate in the usual manner. A valve 52 is reciprocally mounted in chamber 53 within the casing. Valve 52 is urged downwardly by a spring 54 into engagement with the bellows 51. An adjusting nut 55 is provided to vary the pressure of spring 54. Valve 52 has an annular recess S6 which is sealed by means of upper :and lower 0-rings 57.

Casing 49 has a lower port 58 in constant communication with the space in chamebr 53 bounded by the walls of recess 56 and connected to conduit- 44.

Casing 49 also has an upper port 59 in selective communication with the space in chamber 53 bounded by the walls of recess 56 and connected by means of conduit 60 with a port 61 in member 5 communicating with passage 1d.

Casing 49 also has an air bleeder port 62 located below valve 52.

Chamber 17 of member `4 has an inlet 63 which, in operation of the device, is arranged to be connected to a supply or fluid such as air under pressure.

Means for manually depressing valve 22 to close the same comprises a shaft 64 journalled inthe wall of mem` ber 4, a lever arm 65 carried by the inner end of the shaft and engaging the valve head 24, anda knob 66 on the outer end of the shaft for imparting rotation thereto.

In describing the operation, it will'be assumed that the 3 apparatus described is installed in association with a prime mover with the conduit 31 connected appropriately in the lubricating oil circuit of the prime mover, the thermostaticV element 50 located in the coolant of the prime mover, and the chamber 17 supplied with air under pressure through inlet 63.

Under normal conditions the parts of the apparatus are as shown in Figure l. Valve 22 is held open under the influence of spring 27 and pressure of oil in chamber 29, which acts on diaphragm 9 to hold the valve in open position. Diaphragm is moved downwardly by presA sure of oil in chamber 29 to hold the head 35 of pilot valve 33 on its seat. The compressed air in chamber 17 fills the passage 18 and through opening 19 has contact with the top face of diaphragm 8. The compressed air also fills conduit 60, the space in chamber 53 of thermostat unit 48 bounded by the walls of valve recess S6, conduit 44, the space in passage 32 bounded by the walls of valve recess 37, passage 47, and chamber 16 below diaphragm 8. The combined action of the air under pressure in chamber 16 and the spring-pressed piston 13 holds the diaphragm in upper position and thus closing opening 19 and the opening of passage 12. lt will be understood that such combined action over'oalances the air under pressure acting on the upper face of diaphragm S through opening 19.

It will be observed that, under normal conditions as described, no parts of the apparatus are in motion and no flow of air under pressure is required, it being merely necessary to maintain under pressure the air in the circuit described. Moreover, it will be apparent that the air circuit described constitutes in etect, a single air passage which is continuous except for interruption by diaphragm 8, such air passage being, however, subject to interruption at other points by valves 22, 33 and 52.

Should the oil pressure fail, spring 40 will move valve 33 upwardly because of the release of pressure upon diaphragm 10. Port 46 and passage 47 then communicate with the space in passage 32 below valve 33 and the air under pressure in passage 47 and chamber 16 bleeds to atmosphere through port 41. The compressed air in passage 18 then moves diaphragm 3 downwardly, as shown in Figure 2, thus placing passages 18 and 12 in communication. The air under pressure owing into passage 12 thus actuates whistle 11 to sound an alarm.

Should the coolant temperature rise above a safe limit, the bellows 51 of thermostat 50 will move valve S2 upwardly to place port 58 in communication with the space below valve 52 in chamber 53 and thus the compressed air in chamber 16, passage 47, and conduit 44 bleeds to atmosphere through port 62, and the alarm device 11 is sounded in the manner previously described. The adjusting nut 55 will facilitate setting the alarm to operate for whatever temperature is regarded as the safe operating limit of the particular prime mover in which the device is installed.

With reference to the valve 22, it will be observed that, under normal and alarm conditions, this valve remains in the open position unless manually shifted to closed position 'while the whistle is blowing. This valve is incorporated in the system to enable the operator to shut off the alarm while investigating the cause of the alarm. In the event that the prime mover is stopped intentionally, the alarm will sound due to low oil pressure and it may be shut olf by manually closing valve 22. The air pressure acting on the valve head 24 will hold valve 22 closed and stop the whistle only if no oil pressure acts on diaphragm 9. lf the prime mover is stopped, the whistle sounds and is manually shut oft, whereupon the apparatus is reactuated when the oil pressure is raised by starting the prime mover.

The apparatus may be readily employed to actuate the clutch of the prime mover or other device for arresting operation of the prime mover under alarm conditions. The port 67 in member 2 may be employed to provide a connection for conducting air under pressure for actuation of such devices.

The apparatus described results in the provision of a simple and rugged self-contained alarm system. Since the operating medium is compressed air, it is safe to use in explosive atmospheres. All parts of the device are restrained from vibration, and its associated wear, by means of springs, air pressure, or sealing rings, or combinations thereof. Since sealing of the various valves is accomplished by use of resilient diaphragms and sealing rings, there are no precise metal to metal fits which might be ditiicult to manufacture, maintain and repair. As previously indicated no air or other operating medium is consumed until alarm conditions arise. Thus, no lubrication is required and no moisture will condense in the device.

It will also be observed that the compressed air and oil pressure passages are completely isolated from one another by the rubber or like oil resistant diaphragm. Thus, the possibility of disastrous air leaks into the engine oil or equally dangerous engine oil leaks to atmosphere is substantially eliminated. However, it will be observed that should a leak occur in any of the various associated elements, the arrangement is such that resulting conditions will cause sounding of the alarm.

The various diaphragms are restrained from excessive flexing movement in the structure illustrated. Thus, member 6 is provided with a transverse bar 63 between thc diaphragms 9 and 10, while outward movement of such diaphrgams is limited to the small seating movement of the respective valves. Similarly, diaphragm 8 has but limited downward movement in response to air pressure.

It will be apparent that the apparatus described and illustrated is of a most compact nature and may be conveniently and easily installed in operative relation with a prime mover.

I claim:

l. An alarm device for indicating unsafe operating conditions in a prime mover which comprises an air-operable signal, means forming a passage for air under pressure to operate said signal, said passage having an opening, a iirst diaphragm overlying said opening, resilient means normally holding said diaphragm in closing relation to said opening, means forming a second passage having one end communicating with one side of the diaphragm and its other end communicating with the other side of said diaphragm, means for lling said second passage with a supply of air under pressure, a valve in said second passage, means forming a chamber arranged for constant communication with the lubricating oil of said prime mover, a second diaphragm forming one wall of said chamber and engaging said valve, said second diaphragm holding said valve in open position in response to pressure of said lubricating oil, and resilient means moving said valve to closed position to interrupt said second passage in response to a drop vin pressure in said lubricating oil, said closing movement of said valve acting to vent to atmosphere the air under pressure in the portion of said second passage on one side of the valve.

2. An alarm device as defined in claim l. including a thermostatic unit having a chamber therein, said chamber having a pair of ports each communicating with said second passage, a valve recprocally mounted in said chamber and normally placing said ports in communication, and a thermostat arranged for location in the coolant system of said prime mover, said valve being operably connected to said thermostat to move the valve and interrupt communication between said ports said interrupting movement of the valve acting to vent to atmosphere the air under pressure in the portion of said second passage in communication with one of said ports.

3. An alarm device for indicating unsafe operating conditions in a prime mover as defined in claim 1, including a second valve in said second passage, a third diaphragm constituting another wall of said chamber and normally urging said second valve into open position, and manually operable means for closing said second valve to interrupt said second passage.

4. An alarm device for indicating unsafe operating conditions in a prime mover which comprises a composite unit having a top member, an air-operable signal mounted on said top member, a passage in said top member for air under pressure to operate said signal, a second member, a rst diaphragm between said members, a first chamber in said second member communicating with one side of said diaphragm, resilient means in saifd chamber urging said diaphragm into closing relation with said passage, said second member having a second chamber therein, a third member constituting a wall of said second chamber, means for admitting air under pressure to said second chamber, a first connecting air passage in said members extending from said second chamber to the other side of said diaphragm, a manually operable valve for closing said passage, a fourth member having a chamber therein arranged for communication with the lubricating oil system of said prime mover, a second diaphragm constituting one Wall of said last-mentioned chamber and engaging said valve to urge it into open position, a bottom member having a chamber therein, a second connecting air passage in said members, said last mentioned chamber extending from said first chamber in said second member, a conduit connecting said bottom member chamber with said first connecting passage, a valve in said bottom member chamber in normally open position to place said second connecting passage in communication with said conduit, a third diaphragm constituting another wall of said fourth member chamber and bearing on said last-mentioned valve to retain it in said normally open position, resilient means urging said last-mentioned valve to closed position to interrupt communication between ysaid second connecting passage and said conduit, and means responsive to closing movement of said last-mentioned valve for bleeding to atmosphere air under pressure in said second connecting passage.

5. An alarm device as defined in claim 4 including a thermostatic control unit disposed in said conduit, said unit having thermostatic means for disposition in the coolant system of said prime mover, and valve means in normally non-interrupting relation to said conduit but mov- 20 able by said thermostatic means to interrupt said conduit.

References Cited in the file of this patent UNITED STATES PATENTS 823,114 Gerard June 12, 1906 

